Use of organic dopants to enhance acetylene hydrogenation catalysts

Abstract

A composition comprising a supported hydrogenation catalyst comprising palladium and a support, wherein the supported hydrogenation catalyst is capable of selectively hydrogenating highly unsaturated hydrocarbons to unsaturated hydrocarbons; and a dopant comprising a fluorene structure. A method of making a selective hydrogenation catalyst including contacting a support with a palladium-containing compound to form a supported-palladium composition; contacting the supported-palladium composition with a dopant comprising a fluorene structure group to form a selective hydrogenation catalyst precursor; and reducing the selective hydrogenation catalyst precursor to form the selective hydrogenation catalyst. A method of selectively hydrogenating highly unsaturated hydrocarbons to an unsaturated hydrocarbon enriched composition by contacting a supported catalyst comprising palladium and a dopant comprising a fluorene structure with a feed comprising highly unsaturated hydrocarbon under conditions suitable for hydrogenating at least a portion of the highly unsaturated hydrocarbon feed to form the unsaturated hydrocarbon enriched composition.

What is claimed is: 
     
       1. A composition comprising:
 a supported hydrogenation catalyst comprising palladium and an inorganic support selected from the group consisting of aluminas, silicas, titanias, zirconias, aluminosilicates, spinels, and combinations thereof, wherein the supported hydrogenation catalyst is capable of selectively hydrogenating highly unsaturated hydrocarbons to unsaturated hydrocarbons; and 
 a dopant, wherein the dopant comprises a fluorene structure 
 
       
         
           
           
               
               
           
         
       
     
     
       2. The composition of  claim 1 , wherein the dopant further comprises at least one substituent selected from the group consisting of carboxyl groups, hydroxyl groups, carbonyl groups, amide groups, phenyl groups, substituted phenyl groups, and combinations thereof. 
     
     
       3. The composition of  claim 2 , wherein the at least one substituent is located on the 1, 2, 4, or 9 position of the fluorene structure. 
     
     
       4. The composition of  claim 3 , wherein the dopant comprises 9-phenyl-9-fluorenol, 9-hydroxyfluorene, 2-hydroxyfluorene, 9-(2-(hydroxymethyl)phenyl)-9-fluorenol, fluorene-9-carboxylic acid, fluorene-1-carboxylic acid, fluorene-4-carboxylic acid, fluorenone, fluorene, or a combination thereof. 
     
     
       5. The composition of  claim 1 , wherein the dopant has a boiling point of greater than or equal to about 200° C. 
     
     
       6. The composition of  claim 1  further comprising at least one selectivity enhancer selected from the group consisting of Group 1B metals, Group 1B metal compounds, silver, silver compounds, fluorine, fluoride compounds, sulfur, sulfur compounds, alkali metal, alkali metal compounds, alkaline metals, alkaline metal compounds, iodine, iodide compounds, and combinations thereof, disposed on the inorganic support. 
     
     
       7. The composition of  claim 1 , wherein the palladium is present in an amount of from about 0.005 wt. % to about 5 wt. % based on the total weight of the catalyst. 
     
     
       8. The composition of  claim 1 , wherein the dopant is present in an amount of from about 0.005 wt. % to about 5 wt. % based on the total weight of the catalyst. 
     
     
       9. The composition of  claim 1 , wherein the inorganic support has a surface area of from about 2 m 2 /g to about 100 m 2 /g, and wherein greater than about 90 wt. % of the palladium is concentrated near a periphery of the inorganic support. 
     
     
       10. A method of making a selective hydrogenation catalyst, the method comprising:
 contacting an inorganic support selected from the group consisting of aluminas, silicas, titanias, zirconias, aluminosilicates, spinels, and combinations thereof with a palladium-containing compound to form a supported-palladium composition; 
 contacting the supported-palladium composition with a dopant to form a selective hydrogenation catalyst precursor, wherein the dopant comprises a fluorene structure 
 
       
         
           
           
               
               
           
         
       
       and
 reducing the selective hydrogenation catalyst precursor to form the selective hydrogenation catalyst. 
 
     
     
       11. The method of  claim 10 , wherein the dopant further comprises at least one substituent selected from the group consisting of carboxyl groups, hydroxyl groups, carbonyl groups, amide groups, phenyl groups, substituted phenyl groups, and combinations thereof. 
     
     
       12. The method of  claim 11 , wherein the at least one substituent is located on the 1, 2, 4, or 9 position of the fluorene structure. 
     
     
       13. The method of  claim 12 , wherein the dopant comprises 9-phenyl-9-fluorenol, 9-hydroxyfluorene, 2-hydroxyfluorene, 9-(2-(hydroxymethyl)phenyl)-9-fluorenol, fluorene-9-carboxylic acid, fluorene-1-carboxylic acid, fluorene-4-carboxylic acid, fluorenone, fluorene, or a combination thereof. 
     
     
       14. The method of  claim 10 , wherein the dopant has a boiling point of greater than or equal to about 200° C. 
     
     
       15. The method of  claim 10  further comprising contacting the inorganic support, the supported-palladium composition, the selective hydrogenation catalyst precursor, or the selective hydrogenation catalyst with at least one selectivity enhancer selected from the group consisting of Group 1B metals, Group 1B metal compounds, silver, silver compounds, fluorine, fluoride compounds, sulfur, sulfur compounds, alkali metal, alkali metal compounds, alkaline metals, alkaline metal compounds, iodine, iodide compounds, and combinations thereof. 
     
     
       16. The method of  claim 15 , wherein the selectivity enhancer comprises elemental silver, silver nitrate, silver acetate, silver bromide, silver chloride, silver iodide, silver fluoride, or combinations thereof. 
     
     
       17. The method of  claim 15 , wherein the selectivity enhancer comprises elemental alkali metal, alkali metal fluoride, alkali metal chloride, alkali metal bromide, alkali metal iodide, alkali metal oxide, alkali metal carbonate, alkali metal sulfate, alkali metal phosphate, alkali metal borate, potassium fluoride, or combinations thereof. 
     
     
       18. The method of  claim 17 , wherein the selectivity enhancer is present in an amount of from about 0.01 wt. % to about 5 wt. % based on the total weight of the selective hydrogenation catalyst. 
     
     
       19. The method of  claim 15 , wherein the selectivity enhancer comprises silver and potassium fluoride. 
     
     
       20. The method of  claim 15 , wherein contacting the inorganic support, the supported-palladium composition, the selective hydrogenation catalyst precursor, or the selective hydrogenation catalyst with the least one selectivity enhancer comprises incipient wetness impregnation. 
     
     
       21. The method of  claim 10 , wherein the palladium is present in an amount of from about 0.005 wt. % to about 5 wt. % Pd based on the total weight of the selective hydrogenation catalyst. 
     
     
       22. The method of  claim 10 , wherein the dopant is present in an amount of from about 0.005 wt. % to about 5 wt. % based on the total weight of the selective hydrogenation catalyst. 
     
     
       23. A selective hydrogenation catalyst prepared according the method of  claim 10 . 
     
     
       24. The method of  claim 10 , wherein contacting the inorganic support with the palladium-containing compound to form the supported-palladium composition and contacting the supported-palladium composition with the dopant to form the selective hydrogenation catalyst precursor comprise incipient wetness impregnation. 
     
     
       25. A method of selectively hydrogenating highly unsaturated hydrocarbons to an unsaturated hydrocarbon enriched composition, the method comprising:
 contacting a supported catalyst comprising palladium and a dopant with a feed comprising highly unsaturated hydrocarbon under conditions suitable for hydrogenating at least a portion of the highly unsaturated hydrocarbon feed to form the unsaturated hydrocarbon enriched composition, wherein the dopant comprises a fluorine structure 
 
       
         
           
           
               
               
           
         
       
     
     
       26. The method of  claim 25 , wherein the highly unsaturated hydrocarbons comprise acetylene, methylacetylene, propadiene, butadiene, or a combination thereof. 
     
     
       27. The method of  claim 25 , wherein the conditions suitable for hydrogenation include conducting the step of contacting at a temperature less than about the boiling point of the dopant. 
     
     
       28. The method of  claim 27  further comprising increasing the temperature to a temperature greater than or equal to about the boiling point of the dopant.